Process for the drying and curing of lumber



0. E. JACOBS. PROCESS FOR THE DRYING AND CURING 0F LUMBER. APPLIEATION FILED SEPT. 15. 1916.

1,333,848; Patented Mar. 16, 1920.

I 51mm OSCAR E... dAoobs /m/hwooe l I I UNITED STATES PATENT OFFICE. 5

OSCAR E. JACOBS, 0F KALAMAZOO, MICHIGAN.

IROCESS FOR THE DRYING AND CURING OF LUMBER.

To all whom it may concern:

Be it known that'I, OSCARE. J Aoons, acitizen of the United States, residing at the city and county 'of Kalamazoo, State of Michigan, have invented certain new and useful Improvements in Processes for the Drying andeCuring of Lumber, of which the following is a specification.

This invention relates process for the drying and curing of lumber.

The object of this invention is to eliminate all moisture from the lumber without i juring thetexture in any way.

I accomplish the object of my invention by the process described fined and pointed out in the claims.

' y process may be carried out in an apparatus similar .to that illustrated in U. Patent No. 217,002, issuedJuly 1, 1879, to L. S. Robbins, for process or apparatus for treating" wood or, lumber; or in an' app-aratus comparable to that appearing in U. S. Patent No. 1,186,555, issued June 13, 1916, to Derby and Dargie, for process for the treatment of wood. The details of construcsteam chamber or tion of such apparatus, however, are not material and can be greatly modified.

I illustrate an apparatus'adapted to carry out my invention, it being an apparatus that may be made use of for various purposes, and m invention may be carried out in any suita' le apparatus, this being illustrated merely as an effective apparatus for the purpose.

The apparatus illustrated comprises a kiln 1 in which there is a track 2 for receiving a truck 3 with a load of lumber or timber 4: Which is piled with suitable spaces5 between it. The kiln door 6 is provided with a gasket 7 for hermetically closing the'same. 'A steam. pipe 8 controlled by the valve 9 delivers steam to the chamber or kilnand the exhaust pipe 10 connects to a vacuum pump 11 for discharging the vapor and air from the inside of the kiln outwardly through the pipe 12. The pump 11 is operated through the piston rod 13 and eccentric 14 carried upon shaft 15 driven by the tight and loose pulley '16. A steam pipe 17 delivers toa coil 1 within the kiln the circulation discharge 19 extending out through the wall of the kiln. Pipe 20 is for exhausting the steam after the pressure treatment. This provides a to an improved,

face of the lumber or quality of the same -inch, and maintain the in the following specification. The invention is clearly de- Specification of Letters Patent. Patented Mar; 16, 1920, Application filed September 15, 1916.

Serial No. 120,393.

suitable apparatus for carrying out the steps of my improved process.

The first step of my improved process is to in-close the lumber in asuitable cylinder or retort which can be closed air tight, within which 'is disposediasteam coil for heating the same. I heat the lumber to temperature of about 100 F. for 20 or 30 minutes by means of the steam coils until the suris air dry and fairly warm. For the second step, I introduce live steam at a temperature below 250 F., preferably at a pressure of'about 20 pounds to the square same for about 20 minutes for the treatment of lumber about one inch in thickness. I have found that a temperature of above 250 F. is likely to injure the quality of wood fiber.

For-the third step, after the wood has thus become thoroughly saturated with the hot steam, I blow off the steam, which takes a period of 2 or 3 minutes and then connect a vacuum pump and produce a vacuum of from 20 to it will be very clear that there is little or no air in the cylinder or retort when thesteam is blown off and the vacuum is created by the drawing off of the vapor itself. I endeavor to keep the.

temperature of the wood within the retort in the early stage of the evaporationsubstantially' at or above the boiling point. within the vacuum chamber. To do this, I

turn on the steam in the coils that were used for heating in the first place and then maintain the temperatureht. about 100. to 120 F. so that the moisture inv the wood will be very rapidly evaporated. Of course,-it

is not possible to materially heat the wood after the vacuum is created, but I find that it is possible by the use of the coils, to substantially maintain the temperature at about 100 F. I maintain the temperature a little higher, about 120, at the finish. I maintain the vacuum as near as may be for a" 28 inches, keeping the pump in operation to carry ofl the moisture as it' expands into vapor from the wood. From this treatment,

This process avoids any checking of the Wood and dries the same apparently from the inside out so that the entire fiber of the lumber that is subjected to the whole treatment is equally dried and there is no checking or splitting or any undue hardening of the surfact or of any part of the lumber that has been submitted to the treatment.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is: I

1. The process of treating lumber consist ing of inclosing the same in a suitable retort and heatin the same to about100 F. for a period su icient to thoroughly air dry the surface of the same then subjecting the same to live steam at about pounds pressure and not to exceed 250 heat until the entire substance of the lumber has become evenly heated, thereupon blowing ofi stean'l and subjecting the chamber to a vacuum actlon and maintaining heat within the vacumesses um and continuing the vacuum. action with the lumber at a temperature of about 100 to 120 F. until the same is dried.

2. The process of treating lumber consisting of inclosing the same in a suitable retort and heating the same to about 100 F. for a period sufficient to thoroughly air dry the surface of the same then subjecting the same to live steam at about 20 pounds pressure and not to exceed 250 heat until the entire substance of the lumber has become evenly heated, thereupon blowing off steam and subjecting the chamber to a vacuum action until the same is dried.

In witness whereof, I have hereunto set my hand and seal in the presence of two witnesses.

oscan n. JACOBS. [n 5.

Witnesses:

THOMAS W. BaRLow, R. M. DANronTH. 

